Pine needles are acidic, but are often blamed for poor lawn conditions when they are not necessarily the cause. The needles themselves eventually decompose and create a mulch layer that releases nutrients back to the ground. Now a few needles themselves are not bad, but larger quantities can smother the weaker grass and eventually kill it off. The real culprits are the lack of sun caused by the tree, and the lack of sufficient water because the tree roots are competing with the grass and often win. It can be difficult to maintain lawn under mature pines cause of the above reasons. Removing the needles is not always the answer. If the trees are very tall you can prune the lower branches to allow more sun, but you still have the water issue. If this is not an option than your next and healthiest option is eliminate the grass under the tree completely and create a mulch bed under the canopy.

I have heard both no sun under pines and root competition and believe both, but what about dropping sap? I've trimmed many a pine and found sap leaks where there were no obvious wounds.

Dream of all the money you could make today and then realize that this is not about the money.... it's about the commitment, the sunrise coffee, the sunset beer, the smile on the customer's face and the knowledge that what you did today did more than make you money.... it brightened lives!